Improvement in chucks for rock-drills



UNITED STATES PATENT OEEToE.

JOSEPH C. GITHENS, OF NEW YORK, N. Y.

IMPROVEMENT IN CHUCKS FOR RQGK-DRILLS.

Specification forming part of Letters Patent No. 164,99 l, dated June 29, 1875 application filed Mary 15, 1875.

To all whom yit may concern:

- Be it known that 1, JOSEPH C. GITHENs, ot the city, county, and State of New York, have invented a new and useful Improvement in BitUhucks for Steam Rock-Drills, of which the following is a specification:

Figure l is a front view ot' my improved chuck. Fig. 2 is a detail longitudinal section ot' the same, taken through the line was, Fig. 1. and Fig. 3 is a detail crosssection of the same, taken through the line y y, Fig. 1.

Similar letters ot' reference indicate corresponding parts.

rlhe invention will rst be fully described in connection with drawing, and then pointed out in the claim. Y

A represents the piston-rod of a steam roekdrill, upon the lower end of which is formed an enlargement, a. In one side of the lower end of the piston-rod A is formed a groove, extending through the enlargement al, and the bottom of which is rounded out, so as to be semi-cylindrical in form. This groove is made of such a depth that the center `of the cylinder, ot' which its bottom is a part, may be the axis of thepistonlrod A. B is a key, fitted into the groove in the piston-rod A, and the inner edge of which has a ,half-round groove formed in it, to correspond with the bottom of the groove in thepiston-rod, so that when the key B is in place a cylindrical hole will be formed to receive the bit C'. The key B has a swell or enlargement lformed upon the outer side of its middle part, which is notched ,and have nuts d screwed upon their ends. In

the bottom of the groove in the pistonrod A, and in the bottom of the groove in the inner edge ofthe key B, are formed longitudinal grooves a2 b2, as shown in Fig. 3, so that the lbit C, when clamped in the clutch, may be held in at least four points, whether its shank may loe ofthe ordinary octagonal form, or turned down into a rounded form. rlhe inner edge of the key B has a wide transverse notch formed in it, that its end parts only may bear upon the bit C.

By this construction, the end parts of the keyB bearing upon the bit C andthe U-bolt D grasping the middle part ot the key, there will be a slight yield or spring to the key, which will cause it to hold the bit C more firmly.

Having thus described my invention, l claim as new and desire to secure by Letters Patent- The combination of the grooved 'and .notched key B, and the U-bolt D, with the grooved enlarged end ot the piston-rod A, substantially as hereinshown and described;

' JOSEPH O. GITHENS.

Witnesses:

J AMES T. GRAHAM, ALEX. F. RoEERTs. 

